The present invention relates to a structural reinforcing part for an air deflection device on a motor vehicle, a corresponding air deflection device and a method for the production of a shaped structural reinforcing part.
Air deflection devices are typically used as wind deflectors or wind blockers in the motor vehicle sector. In conjunction with a sliding roof system, they perform the function, especially when the sliding roof is open, of suppressing or preventing any troublesome noise caused by periodic changes in air pressure, which is perceptible as booming within the vehicle. For this purpose, a wind deflector should generally be arranged in the region of the front edge of a sliding roof aperture in the direction of travel of the vehicle.
When the sliding roof is open, a movably mounted extender portion of the wind deflector moves into a use or extended position, in which it is raised relative to a home position. Raising the extender stretches an air-permeable surface element between the extender and a base part, which is typically fixed on the vehicle. If the vehicle is in motion, extending the surface element leads to a deliberate local swirling of the air, which is an effective means of counteracting the occurrence of audible fluctuations in air pressure.
A wind deflector known per se is disclosed by DE 102 10 142 A1, for example. This wind deflector has an extender connected pivotably to a base element, and an air-permeable and flexible deflector element being arranged on the base element and on the extender. Also provided is an extender spring, which pushes the extender into an extended position when the sliding roof is open, in which position, the deflector element is stretched between the base part and the extender. In this arrangement, the deflector element is preferably secured on the base element and/or on the extender by means of an injection-molding process.
A wire leg spring, which functions as an extender spring and serves as a hinge between the extender and the base part, is furthermore provided. The legs of the leg spring can be inserted into the base element and the extender and can be latched there mechanically. It is furthermore possible to insert the leg spring into the mold for the base element and the extender, and injection-mold it directly into place in situ.
It is necessary in terms of production engineering to secure or fix the deflector element on the extender or base part before the extender or base part is molded on or encapsulated in plastic. For this purpose, a shaped, structural reinforcing part is typically provided for the extender and/or the base part, and is typically in the form of a metal hoop, on which the deflector element is secured before the metal hoop is encapsulated.
It has proven disadvantageous that the metal hoop to be encapsulated in the injection-molding process has relatively large component tolerances, owing to the way in which it is produced. When the metal hoop to be encapsulated is inserted into an injection mold, this can lead to the metal hoop being subject to elastic deformation in bending, at least in a certain area or areas. Immediately after the injection-molding operation, in the course of which the metal hoop is encapsulated with a thermoplastic elastomer for example, restoring forces associated with bending elasticity can emerge in the encapsulated metal hoop, and these can lead to deformation of the extender or the base part encapsulated within plastic.
In addition, there is the risk that the wall thickness of the plastic encapsulation will vary locally from one area to another, owing to restoring forces associated with bending elasticity in the metal hoop insert. It may also happen that the metal insert to be encapsulated will rest against the inside of the injection mold during the injection-molding process, with the result being that areas of the metal insert will emerge visibly in the encapsulating plastic layer after the injection-molding process is complete.